Different lenses

[Andrea Weissenseel]

Are you all using different lenses for different jobs ? I wonder cause at the moment I have a pretty hard time to cut some very delicate designs in 10 mil plastic. The first tests with the material yesterday showed that it cuts pretty good, but the cut is getting pretty wide cause of melting. I'll fine tune my settings on Monday - I just wonder if a other, than the standard 2" lens would make it easier to make real fine cuts

Andrea

[David Fairfield]

Hi Andrea

Sometimes I use the 1.5" lens for very fine cutting and engraving. But there is not a lot of difference; its only visible under magnification. For example, this 1/87 scale clock I can only do with the 1.5" lens, it disintigrates with the 2". So the lens definitely has its uses.

But I think the problem with wide cuts in plastic is due to the material melting away from the heat source. I think you will get better results by experimenting with your settings. Dropping the frequency down can really help cutting plastic.

Dave

[Andrea Weissenseel]

wow that clock is really tiny :D looks great !

I realized that there is a lot of difference when you experiment with the frequency. On my machine the highest "normal" setting is 1524, after that is "X" which is a continuous beam. When set to 1524 plastic is not cut through

[Gary Hair]

"normal" setting is 1524, after that is "X" which is a continuous beam.

I thought "X" was "Automatic", meaning that it set the frequency to the same number as the dpi?

Gary

[Rodne Gold]

If you cant cut thru at 1000 ppi , something is wrong - acrylic will cut at 500 easily.
I think you might have a beam alignment issue or you need to "fine tune" your Auto focus - they supply a manual gauge - use it to check your autofocus and the laser engraver itself has a tuning adjustment on the control panel.
Why I think something is wrong is that the 2" lens should cut the 10 mil stuff(assuming it is actually acylic) with almost no kerf or cut width
A 1.5 " lens or a 4" is a waste of money unless you have VERY specific reasons for using em.. For cutting , the 1.5" lens needs to be focussed absolutely perfectly and the material needs to be real thinn and perfectly flat , good for cardstock , paper , kiss cutting , inlay work etc.
4" lens has less power density - it can cut thicker stuff with straighter sides but you can easily run out of power. Also good when you need clearance from the flying optic and the edge of an item - like missing the sides of a bowl when engraving the inside of it (tho you can use your "engrave from centre" to do this as well if the gantry clears the item)

[Martin Reynolds]

I found that the X setting boosts power by almost 50% over the 1524 setting. So you have to significantly reduce the speed to get the laser to cut.

However, getting off of X allows the machine to keep the same power for lines and curves. The Explorers are very slow at drawing curves.

What this means is that you get better consistency with 1524 and lower, but at the price of slower cutting. I go for speed.

[Mike Null]

I agree with Rodney. At that thickness there should be minimal kerf if your settings are correct.

[Richard Rumancik]

Andrea, I have used my 1.5" lens a lot for precision work - the spot size seems to be quite a bit smaller (I can say exactly as the manufacturers will spec a wide reange for all) but I'd say .005" diameter for my 2" lens and maybe .003" diameter for my 1.5" lens.

For small items, flatness over the whole table might not be such an issue as you often only use a small area. I doubt David makes a sheet of clocks at a time. You might be restricted to a smaller working area but I have not had a big problem with dept of field limitations.

I would not be hasty in ruling out a 1.5" lens. I realize the lenses are not inexpensive.